hush: tighten up "for" variable name check.

Add TODOs.
 Disable redir4.right part where we differ from bash.
 It is not a bug per standards.
 Add a few tests, one is in hush-bugs section:
 and_or_and_backgrounding.right. It will likely bite users
 in real world usage.

shell/hush_test/hush-misc/redir1.tests

@@ -27,7 +27,7 @@ var=ok
 { var=bad >shell_test_$$; } &
 # cant use usleep as it isnt standard in $PATH --
 # we fail when testing busybox compiled solely as "hush"
-sleep 1
+wait
 echo "Test 4:  var:$var"
 test -f shell_test_$$ && echo "File created:ok"